Electromagnetic actuator



J. H. JQHNSON ELECTROMAGNETIC ACTUATOR April 17, 1951 Filed Nov. 16, 1949 3nve ntor JAMES H. JOHNSON M #5 41 Gttomeg Patented Apr. 17, 1951 5.

ELECTROMAGNETIC ACTUATOR James H. Johnson, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application Novemberlfi, 19,49,Serial No. 127,610

' 3 Claims. (Cl. 175--338) This invention relates to electromagnetic actuators of the pivoted armature and movable plunger type and more particularly to means for elimination of noise of engagement and rebound of an armature for such actuators.

The copending application of Willis H. Gille, Serial No. 127,607, filed November 16,1949, is directed to a stop member or structure for'electromagnetic actuators to eliminate noise of engagement and rebound of the armature. The present invention relates to an improvement in actuators of the type disclosed therein.

It is an object of this invention to provide in an electromagnetic actuator of this type a core structure having a flexibly mounted'core or stop member so positioned that a predetermined air gap between the core. and remaining magnetic structure is maintained upon operation of the.

electromagnet.

Another object of this invention is to provide, a simplified mounting for a movable core member.

Still another object of this invention is to provide in an actuator of this type a. core struc-' ture in which uniform attraction is attained between parts thereof during operation and the residual magnetism between" the parts is substantially prohibited.

These and other objects of this invention will' My improved electromagnet is shown in the drawings in the form of a clapper-type electromagnet or relay having a magnetic core structure which includes a stationary core member Iilg generally L-shaped in form having a main or base portion I I with a plurality of upstanding portions I2, I3 are separated into a centrally located portion I2 upon whichv an armature I5 is adapted to be pivoted and a pair of side portions l3- which serve as backstops for the armature inv a manner. later to be described. Magnetic core structure In including the main portion II and. upstanding portions I2 and 13 as, well as armature I5 are fit).

ment. As previously noted. brass mounting plate.

2 made of a magnetic material of relatively good permeability, such as soft iron, to provide a con-. tinuous magnetic circuit. Armature I5 is generally bar-shaped in form and has attached thereto at its pivoted extremity a brass mounting plate IB which is secured to the armature I5 through rivets I1 and a reinforcing plate I8, all pieces being made of a non-magnetic material. As shown in Figures 1 and 2, the nonmagnetic mounting plate I6 has a pair of notches 2i) therein and a centrally located aperture 2| the purposes of which will become evident as the disclosure proceeds. Notches 20 of plate It re-v ceive projecting guide members 22 of a mounting plate 23 which is attached to upstanding portion I2 of core member Ill. Mounting plate 23 is attached to upstanding portion I2 by any suitable means, such as by rivets, and may be made of any material such as iron or brass. With the exception of the guide pins 22, plate 23 is so positioned on the upstanding member I2 that it terminates below the upper edge of the upstanding portion I2 so as not to be in contact with the armature I5. The projecting guides 22 are disposed to one or the other side of the main body of the armature I5 and fit into the slots 20 in the brass mounting plate IE to guide the armature in its pivotal movement. The upstanding portion. I2 of the core structure It is beveled as at 25 and engages the armature I5 in a knife-edge engage- I6 has a centrally located notch on aperture 2| so provided that the upstanding portion I2 of core structure II] can directly engage the armature I5to provide a continuous magnetic circuit at this point.

The lower extremity of mounting plate 23 has a transversely extending flange .26 designed to receive and anchor onev end of a spring 21, the opposite extremity of which is anchored in a. notch or aperture 28 in the extremity of. armature l5. In this manner the armature I5 is biased to an open position or biased for counterclockwisemovement about the pivot formed be tween the. upstanding portion I2 and the armature l5. Side sections I3 of the core structure project up to substantially the same level as the centrally located upstanding portion I2 and are spaced to receive the. extremity of the armature. to provide a backstop therefor. portions of the core structure provide a parallel magnetic circuit for the core structure which is continuous or without an air gap when the armature is in an open or deenergize'd position.

Armature It at its. free extremity carries .a;

Further, these I plunger 30 made of a plurality of laminations of magnetic material and attached to the armature proper by means of rivets 3|. Plunger 30 extends transversely of the main body of armature l5 and is partially disposed within the confines of a coil 33 mounted on an insulating bobbin 34 and secured to the main body portion ll of core structure l0. Coil 33 is mounted on the main portion H of core structure ID by means of a brass sleeve 35 which extends through an aperture 36 in the portion of core structure ID, the sleeve being turned or crimped over at its extremities to securely mount the coil to the core structure In and align the coil with the aperture 36 and armature plunger 30.

Within the aperture 36 formed in the main portion II of core structure I is positioned a core member 40 of magnetic material, the core member being generally square in cross section and designed to align with and fit in the aperture 36. Core member 40 has a flanged portion 4| at its lower extremity of the same general thickness as the L-shaped core member H and disposed to align with the core member I in the same plane. Flanges 4| and the mounting sleeve 35 of coil 33 define an air gap which is very small in comparison to the normal air gap between the core member and plunger 30 when the relay is in an opened position, the former being kept at a minimum allowing only for clearance between the core 40 and spacer member 35. As will be later noted this minimum air gap will always be present in the magnetic circuit, being maintained despite movement of the core under impact of the plunger 30 to prohibit the build-up of residual magnetism in the magnetic circuit.

At the upper extremity of stop member 40 is located a short circuited winding or shading coil 43. The lower extremity of core member 40 is attached by means of spring members 45 to core member II to position the core member within the air gap 30 and locate the core member 4|] with respect to core member The springs 45 are attached by suitable means, such as riveting, at their free extremities to the core member II, as at 46. A pair of springs 45, as can be seen in Figures 2 and 3, are mounted so as to be normal to one another and are attached to the core member 40 at their mid-points by means of a screw 41. A spacer member 48 is positioned within the springs and the core member for spacing purposes. In assembled relationship, the core member 40 is aligned in the aperture 36 and due to the flexibility of springs 45 is movable relative to the core member upon impact with the plunger 30 of armature being biased to a normal position in which the flanges 4| are aligned with the main portion of the core structure. As the core member moves up and down with respect to the core structure, the minimum air gap 4| is maintained.

In operation, the magnetic circuit of this actuator defined by the core structure |0 including the main portion and the upstanding portions I2 and I3, the armature l5, plunger 30, the core member 40, and the flanges 4| is energized by the magnetic flux set up with the energization of the winding 33. Such energization of the magnetic circuit provides magnetic attraction between the core member 4|! and the plunger such that the plunger and armature will be drawn into the confines of coil 30 in the operation of the actuator. As the main air gap of the magnetic circuit, defined by the spacing between the plunger 30 and core member 40, is decreased,

the attraction between these members is increased and the momentum of the armature is consequently increased. Upon engagement of the plunger 30 with core member 40, the core member moves relative to the remaining portion of the magnetic core structure to absorb the momentum of the armature and noise of engagement. With the plunger 30 and core member 40 in contact with one another substantially maximum attraction between the members will be maintained since the air gaps 4| are kept at a minimum and are not varied with this movement of impact. Upon deenergization of the coil 33, the armature l5 and plunger 30 will return to their normal position under the influence of spring 23. Due to the air gaps 4| which are continuously in the magnetic circuit, a build up of residual magnetism will be prohibited and stickiness of the armature to the core member 40 will be prevented.

Figure 5 of the drawings shows another embodiment of this invention in which the core member 40 is mounted on the main portion ll of core structure 10 by means of a flexible mounting plate 50 mad of a rubber or any other suitable insulating and resiliently yieldable material. The mounting plate 50 is similarly attached to the core member 40 by means of a screw 5| threaded through a washer or reinforcing member 52, and is attached to the core member H by any other suitable means such as rivets 53. The operation of this embodiment is the same as that described in connection with Figures 1, 2 and 3, the rubber serving to mount the core member 40 with respect to the core structure such that the momentum of the plunger 30 is absorbed by relative movement between the core member 40 and the remaining portion of the core structure and the noise of engagement is deadened. This mounting through the rubber mounting block 50 also provides for the continued maintenance of the air gaps 4| such that residual magnetism in the magnetic circuit is prohibited.

While the present invention is disclosed in connection with a pivoted armature type electromagnet and is highly advantageous in this type of electromagnetic, it is to be understood that this disclosure is illustratively only and the scope of the invention should be determined by the appended claims.

I claim as my invention:

1. In an electromagnetic actuator, a magnetic core structure including a frame member of magnetic material having an upstanding portion and a transversely extending portion with said transversely extending portion having an aperture therein, a hollow energizing coil for energizing said core structure, a non-magnetic sleeve member extending into said aperture in said transversely extending portion of said frame member being surrounded by said coil and securing said coil on said frame member in alignment with said aperture, armature means including a plate of magnetic material pivotally mounted on said upstanding portion of said frame member and having a plunger attached to the free extremity thereof extending normally thereto and into the confines of said hollow coil, said armature being mounted for pivotal movement about said upstanding portion such that said plunger moves within said coil and out of contact therewith upon energization of said coil and a flow of magnetic flux in said core structure. a magnetic stop member positioned in said aperture of said transversely extending portion of said frame member and being surrounded by said magnetic sleeve to provide a uniform and minimum mounting means attached and its extremities to said transversely extending portion of said frame member and at its center to said stop member to secure said stop member to said frame memher, said stop member being adapted to be engaged by said plunger of said armature means upon energization of said coil and movement of said plunger, said fiexure mounting means permitting movement of said stop member to absorb the impact of engagement between said plunger and said stop member maintaining said minimum air gap and flux flow between said members.

2. In an electromagnetic actuator, a magnetic core structure including a frame member of magnetic material having an upstanding portion and a transversely extending portion with said transversely extending portion having an aper ture therein, a hollow energizing coil for energizing said coil structure, a non-magnetic sleeve member extending into said aperture in said transversely extending portion of said frame member being surrounded by said coil and se curing said coil on said frame member in'alignment with said aperture, armatur means including a plate of magnetic material pivotally mounted onsaid upstanding portion of said frame member and having a plunger attached to the free extremity thereof extending normally thereto and into the confines of said hollow coil, said armature being mounted for pivotal movement about said upstanding portion such that said plunger moves within said coil and out of contact therewith upon energization of said coil and a flow of magnetic flux in said core structure, a magnetic stop member positioned in said aperture of said transversely extending portion of said frame member and being surrounded by said magnetic sleeve to provide a uniform and minimum air gap therebetween, and mounting means including a plate of rubber material attached its extremities to said transversely extending portion of said frame member and at its center to said stop member to secure to said stop member to said frame member, said stop member being adapted to be P engaged by said plunger of said armature means upon energization of said coil and movement'of said plunger, said mounting means permitting movement of said stop member to absorb the impact of engagement between said plunger and said stop member maintaining said minimum air gap and flux fiow between said members.

3. In an electromagnetic actuator, a magnetic core structure including a frame member of air gap therebetween, and fiexure' 6 magnetic material having an upstanding portion and a transversely extending portion with said transversely extending portion having an aperture therein, a hollow energizing coil for energizing said core structure, a non-magnetic sleeve member extending into said aperture in said transversely extending portion of said frame member being surrounded by said coil and securing said coil on said frame member in alignment with said aperture, armature means including a plate of magnetic material pivotally mounted on said upstanding portion of said frame member and having a plunger attached to the free extremity thereof extending normally thereto and into the confines of said hollow coil,

said armature being mounted for pivotal movement about said upstanding portion such that said plunger moves within said coil and out of contact therewith upon energization of said coil and a flow of magnetic flux in said coil structure, a magnetic stop member positioned in said apertur of said transversely extending portion of said frame member and being surrounded by said magnetic sleeve to provide a uniform and minimum air gap therebetween, and mounting means including a plurality of spring members attached at their extremities to said transversely extending portion of said frame member and at their centers to said stop member to secure to said stop member to said frame member, said stop member being adapted to be engaged by said plunger of said armature means upon energization of said coil and movement of said coil and movement of said plunger, said mounting means permitting movement of said stop member to absorb the impact of engagement between said plunger and said stop member maintaining said minimum air gap and flux flow between said members.

JAIWES H. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 919,672 Anderson Apr. 27, 1909 1,226,748 Burnham May 22, 1917 1,230,934 Skinner June 26,1917 1,689,442 Lexa "J Oct. 30, 1928 1,980,393 Evans Nov. 13, 1934 2,145,977 Foster Feb. 7, 1939 FOREIGN PATENTS Number Country Date 17,676 France Oct. 27, 1913 548,717 Great Britain Oct. 21, 1942 

